The invention relates to a method of fastening a sealing bellows to a ball joint as well as to a ball joint comprising a joint housing, a ball stud pivotally received in the joint housing, and a sealing bellows which, with respect to a joint axis, comprises a first axial end of the bellows resting against the ball stud and a second axial end of the bellows fastened to the joint housing, the joint housing for fastening the sealing bellows comprising a seat of the bellows both forming a radial stop as well as an axial stop for the second axial end of the bellows.
Usually, a sealing bellows is provided in ball joints in the transition region between the ball stud and the joint housing for protecting the ball joint against dirt and, if need be, for storing a lubricant. This sealing bellows has to be fastened to the ball stud, on the one hand, and to the joint housing on the other hand in a reliable and permanent manner. Further, the fastening of the bellows should be able to be realized as simply as possible in terms of manufacturing technology in order to reduce the assembly expenditure for the ball joint.
Usually, slotted clamping rings or closed retaining rings are used for fastening the sealing bellows. The elastically expandable clamping rings are clipped in place on one end of the bellows and act upon the sealing bellows radially inwards toward a seat of the bellows. The closed retaining rings, however, are plastically deformed to fix the ends of the bellows to the joint housing and the ball stud, respectively. Due to their slotted design, clamping rings have the disadvantage that they do not exert a radially inward retaining force which is constant in circumferential direction and also may cause damage to the sealing bellows at the edges of their slots.
EP 0 269 836 A2, and corresponding U.S. Pat. No. 4,812,073 A, both of which are incorporated by reference herein in entirety, discloses a device for assembling a sealing bellows to the joint housing of a ball joint. For the purpose of fastening the bellows, a closed sheet metal ring is used which has a cross-section bulging radially inwards. During assembling the bellows, the sheet metal ring is supported by a surrounding ring shoulder of the joint housing and is plastically deformed. Due to its bulged cross-section, an inner diameter of the sheet metal ring decreases during the plastic deformation so that the edge of the bellows is uniformly pressed against a seat of the bellows along the circumference.
EP 0 319 679 A2, and corresponding U.S. Pat. No. 4,921,368 A, both of which are incorporated by reference herein in entirety, also shows a generic ball joint and a method of fastening a sealing bellows to a joint housing of the ball joint. Here, a closed retaining ring is used which is supported by the joint housing and is acted upon by a tool in axial direction and radially inwards, being plastically deformed in this process. Having been plastically deformed, the sealing bellows, to be more precise a peripheral bead of the sealing bellows, is fixed to the joint housing by the retaining ring.
The described ball joints have the disadvantage that the retaining ring rests against the joint housing when the sealing bellows has been installed. As the plastically deformable retaining ring is usually manufactured from metal just like the joint housing, this junction has a very high proneness to corrosion in particular if there is moisture.